Main defects of NbTi alloy and the formation mechanism

The typical defects resulting in the broken wire during the preparation of NbTi superconducting alloy wires was described. The formation mechanism of forging streamline, the Ti-riched segregation resulted from solute redistribution and the mechanism of streamline and black spots were analyzed. The results indicate that the Ti-riched segregation of NbTi alloy could be described by black spots and tree ring in X-ray photograph and the essence of this segregation is channel segregation. It is aimed to provide a method to optimize the preparation technology, which can eliminate the Ti-rich segregation and improve the constituent and microstructure homogeneity of NbTi superconducting alloy.